KR101360404B1 - A Method for Manufacturing Modular Microfluidic Paper Chips Using Inkjet Printing - Google Patents

Abstract

The present invention comprises the steps of: (a) printing an electrode pattern on a substrate using conductive ink and inkjet printing; (b) cutting the printed electrode pattern; And (c) assembling the cut electrode pattern to produce a modular microfluidic chip. Unlike the conventional method of manufacturing a printed circuit board using a patterning agent or a patterning device, the method of the present invention only undergoes a simple printing process using an inkjet printer, thereby simplifying the patterning method and providing various types of chips according to the assembly form of the electrode pattern. It is possible to fabricate and thus provide a low cost, economical and versatile microfluidic chip using the method of the present invention.

Description

A method for manufacturing modular microfluidic paper chips using inkjet printing

The present invention relates to a method of manufacturing a modular microfluidic paper chip using inkjet printing.

Conventional digital microfluidic chips undergo complex manufacturing processes such as photolithography and etching on glass or silicon substrates (RB Fair, Microfluid Nanofluid , 3: 245281 (2007)), the equipment and chemicals used are not only expensive but also very harmful to human body and environment. Most digital microfluidic chips are closed systems (Robert J. Linhardt et al., J. AM. CHEM . SOC ., 131: 11041-11048 (2009)) and analyze the results after various reactions on the chip. In order to remove the cover plate (cover plate) had a disadvantage. The open chip system (Abdelgawad, Park, and Wheeler J. Appl . Phys ., 105: 094506 (2009)) also suffers from the same problems as the fabrication process uses conventional methods to fabricate electrode patterns. Occurs.

Electrowetting (Electrowetting) can be used to control the movement of the fluid electrically, using a digital microfluidic chip. Electrowetting is simply a phenomenon in which the surface tension is changed by electricity. This phenomenon was first discovered in 1870 by Gabriel Lippmann (1845–1921). When water is contained in the glass tube, the glass tube wall has a higher water level than the central part because of the surface tension between the water and the glass tube wall. However, if you use a metal tube instead of a glass tube and turn on electricity, the water that rises along the wall will be higher. This is because the surface tension is stronger with electricity. Lippman called it the "electro-capillary" phenomenon, but the technology hasn't seen much light in the next hundred years. The electrocapillary phenomenon occurred only at low voltages below 1V, and at higher voltages, water decomposed into oxygen and hydrogen. Since 1990, electrowetting has been discovered to control surface tension even at high voltages. Dr. Bruno Berge, France, covered a sheet of metal with a thin insulator and dropped a drop of water on it. Next, when the electricity was applied to the metal plate and the droplets, the droplets spread thinly as the voltage increased. This method made it possible to change the shape of water droplets even at high voltages of tens of volts.

Carbon nanotube (CNT) is a new material in which six hexagonal carbons are connected to each other to form a tubular shape. In 1991, Dr. Sumio Ijima of the Institute of Electrical and Electronics Engineers (NEC) established an electrical discharge. A method was used to analyze the mass of carbon formed on the negative electrode of graphite. Hexagonal shape consisting of six carbons is connected to each other to form a tubular shape. The diameter of the tube is only a few tens of tens of nanometers, which is called carbon nanotubes. Nanometers are one millionth of a meter, usually one hundredth the thickness of hair. Carbon nanotubes have similar electrical conductivity to copper, thermal conductivity equal to the best diamond in nature, and 100 times stronger than steel. Carbon fiber breaks with only 1% strain, while carbon nanotubes can withstand 15% strain. Since the discovery of this material, scientists have been focused on synthesis and applications, and devices using carbon nanotubes, such as semiconductors and flat panel displays, batteries, super fibers, biosensors, and television cathode ray tubes, are being developed extensively.

Republic of Korea Patent No. 10-0523765 provides a method of manufacturing a carbon nanotube array using a nanopattern of organic supramolecular. More specifically, the organic supramolecular thin film is formed on the substrate, and then self-assembly of the organic molecules is induced by heat treatment, and the organic nanomolecule structure formed accordingly is irradiated with UV to irradiate UV-shaped nanopatterns. After forming, it relates to a method for producing a CNT array characterized in that the carbon nanotubes (CNT) arranged on the nanopattern. In the present invention, the patterning process is performed by forming a pattern using self-assembly of organic supramolecules and UV etching in the manufacturing process of the CNT chip, and then patterning the bonded or arranged CNTs to the pattern. This is complicated and has the disadvantage of additionally using UV etching.

Korean Patent Laid-Open No. 10-2011-0060028 provides a carbon nanotube-polymer composite and a method of directly patterning carbon nanotubes in a specific direction using the same. More specifically, in order to form a patterning having an orientation in a specific direction on a substrate comprising a carbon nanotube dispersion solution, a surfactant and a viscous polymer solution, the carbon nanotube-polymer composite and the polymer composite It provides a method for directly patterning carbon nanotubes in a specific direction. The present invention is a method of adsorbing carbon nanotubes, and the sulfuric acid / hydrogen peroxide mixed solution or UV / ozone treatment, and the patterned on the substrate by removing the polymer portion from the carbon nanotube-polymer composite through a separate chemical treatment, Compared to the patterning method, the process is complicated and additional chemical process is required.

Due to the problems of the existing digital microfluidic chip, a digital microfluidic chip based on an open chip of a new technology that can simplify economical and complicated manufacturing processes such as paper, and be used for various synthesis processes. Technology development is urgently needed. The present invention relates to an economical modular microfluidic chip that prints, cuts and combines various types of patterns using carbon nanotube inks, which are conductive inks, and inkjet printing. To solve the above problems by providing a fluid chip.

Numerous papers and patent documents are referenced and cited throughout this specification. The disclosures of the cited papers and patent documents are incorporated herein by reference in their entirety to better understand the state of the art to which the present invention pertains and the content of the present invention.

The present inventors earnestly tried to develop a microfluidic chip which can be manufactured in a low cost, economical and practical way. As a result, a modular microfluidic paper chip was developed by printing various types of electrode patterns using carbon nanotube (CNT) ink and inkjet printing, and then cutting and bonding the electrode patterns. The microfluidic paper chip of the present invention is a prefabricated paper chip that can print electrode patterns of various shapes on a single sheet of paper at once and cut and paste necessary patterns, and a printed circuit board manufacturing method using a conventional patterning agent or patterning device. Unlike the printing process using inkjet printers, the printing process can be simplified, thereby simplifying the patterning method and manufacturing various types of chips according to the assembly form of the electrode pattern.

 It is therefore an object of the present invention to provide a method of manufacturing a modular microfluidic paper chip.

Another object of the present invention is to provide a modular microfluidic paper chip.

Other objects and advantages of the present invention will become more apparent from the following detailed description of the invention, claims and drawings.

According to one aspect of the present invention, the present invention provides a method of manufacturing a modular microfluidic chip comprising the following steps:

(a) printing an electrode pattern on a substrate using conductive ink and inkjet printing;

(b) cutting the printed electrode pattern; And

(c) assembling the cut electrode patterns to produce a modular microfluidic chip.

The present inventors earnestly tried to develop a microfluidic chip which can be manufactured in a low cost, economical and practical way. As a result, a modular microfluidic paper chip was developed by printing various types of electrode patterns using carbon nanotube (CNT) ink and inkjet printing, and then cutting and bonding the electrode patterns. The microfluidic paper chip of the present invention is a prefabricated paper chip that can print electrode patterns of various shapes on a single sheet of paper at once and cut and paste necessary patterns, and a printed circuit board manufacturing method using a conventional patterning agent or patterning device. Unlike the printing process using an inkjet printer, the printing process is simplified, and thus, the patterning method can be simplified and various types of chips can be manufactured according to the assembly pattern of the electrode pattern.

Electrowetting can be used to control the movement of water droplets electrically, and digital microfluidic chips are used. The core of the present invention is to easily print the required electrodes on paper using an inkjet printer and conductive ink, and to assemble chips of various shapes. In order to make digital microfluidic chips, it is important to make electrode patterns of various shapes. In general, complicated processes such as photolithography are required. However, in the present invention, using a CNT ink of the various conductive inks can print a pattern of various shapes on a paper at a time with an inkjet printer, and can also easily produce a chip of the desired shape by cutting out only the necessary portion of the extracted pattern It was made.

Hereinafter, a method for manufacturing the modular microfluidic chip of the present invention will be described in detail.

Step (a): Printing of Electrode Patterns

First, an electrode pattern is printed on a substrate by using conductive ink and inkjet printing.

Inkjet printing used in the present invention is a printer using a piezo electric head of a printer device which is a representative output device of a computer, and forms characters by spraying ink on paper. In other words, the ink particles are discharged and charged on the ground while deflecting them according to the deflection plate to which the voltage controlled by the letter type and the letter position is applied. It is a printer. Ink is initially injected into the ink head and is fired in the form of particles in accordance with the action of the crystal oscillator and gradually hits the ground to form a dot matrix shape.

As used herein, the term “conductive ink” includes conductive materials such as silver and carbon in powder or flake form, and can be drawn or printed on various solid substrates such as paper or film. It means an ink containing the substances present. Conductive inks include, for example, metal inks (eg gold, silver, copper, nickel, gold, platinum, copper and palladium), ceramic inks (eg metal oxides and carbon atoms (or carbon nanotubes)) and molecular inks (eg specialty) Organic materials and polymer materials), but is not limited thereto.

Conductive ink that can be used in the method of the present invention requires a certain amount or more of conductivity to be used as an electrode, preferably the conductive ink is carbon nanotubes (CNT). The carbon nanotubes have better electrical properties than metal materials having excellent electrical conductivity or specific resistance, such as aluminum and copper. Therefore, when using the carbon nanotubes as a conductive material, it is possible to reduce the electrical resistance and also excellent thermal conductivity has the advantage of effectively dissipating heat inside the printed circuit board to the outside.

The carbon nanotubes include, for example, single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, and bundle-type carbon nanotubes, and are preferably multi-walled carbon nanotubes. The multi-walled carbon nanotube electrode exhibits a resistance of 1 kΩ / sq (square) on normal A4 paper and a resistance of 200 kW / sq on photo paper.

The conductive ink may be prepared using a suitable solvent, conductive material, adhesive improver, reducing agent or coupling agent. The solvent may be glycidyl ethers, glycol ethers, vegetable oils, alpha-terpineol or NMP (N-methyl-2-pyrrolidone pyrrolidone), but is not limited thereto. The adhesion promoter may be an acrylic resin or a vinyl resin, and when using a vinyl resin, a mixture containing a silane compound may be used. The reducing agent serves to prevent electrical conductivity from falling when the conductive material is oxidized, and includes, for example, a hydrazine-based reducing agent or an aldehyde-based reducing agent. The hydrazine-based reducing agent includes hydrazine, hydrazine hydrate, hydrazine sulfate, hydrazine carbonate and hydrazine hydrochloride, aldehyde-based reducing agents include, but are not limited to, formaldehyde, acetaldehyde, propion aldehyde.

According to a specific embodiment of the present invention, in order to print various CNT electrode patterns with an inkjet printer, a dispersant may be added to a multiwall CNT and a ball milling operation may be used to make the CNT ink evenly dispersed in water. have. After drawing the electrode pattern using a program such as Photoshop or CAD and printing the electrode of the desired shape on general A4 paper or photo print paper, the printed electrode pattern is cut with a cutting tool, and the patterns By assembling the shape, it can be patterned into a desired shape.

In the specification of the present invention, the term “electrode pattern” means a shape of one unit constituting a path through which a fluid may move when a voltage is applied, and the electrode pattern may be manufactured in various shapes.

According to a specific embodiment of the present invention, the electrode pattern may be manufactured in various forms to make a digital microfluidic chip, for example, (i) dispensing in which water droplets are first made, and (ii) water droplets in a straight line. Linear transport on the electrodes listed, (i) merging several droplets together, (i) mixing the combined droplets by movement, or (i) several droplets meeting and merging or intersecting. It may be manufactured in the form of (crossing), but is not limited thereto.

One of the features of the microfluidic chip of the present invention can easily obtain a variety of electronic patterns using a solid substrate that is easy to handle and cut. The substrate may use a variety of solid substrates used in the art, and includes, for example, easy-to-handle paper (e.g. plain A4 paper, photo print paper), a film (e.g. OHP film) or a plastic sheet, preferably The substrate is paper or film, more preferably paper.

Step (b): Cutting the Printed Electrode Pattern

The electrode pattern printed in step (a) is then cut using a suitable instrument.

According to a specific embodiment of the present invention, since the electrode pattern is printed on paper, it can be easily cut using various cutting tools known in the art, such as scissors, a cutter, and the like. Even when the electrode pattern is printed on the OHP film, it can be cut with scissors.

Step (c): Assembly of the Electrode Pattern

 The cut electrode patterns are assembled to pattern the circuit of the modular microfluidic chip.

The term "patterning" in the context of the present invention means to configure the circuit of the desired form using the cut electrode pattern.

According to a preferred embodiment of the present invention, after the step (c) may further comprise the step of depositing an insulator to form an insulating layer on the electrode pattern.

The insulator may use glass, porcelain or a polymer composition, preferably a polymer composition. When using the polymer composition as the insulator, parylene may be used, for example parylene N, parylene C, parylene D, parylene F, preferably parylene C.

According to another preferred embodiment of the present invention, after step (c) may comprise the step of additionally coating a reinforcing material on the electrode pattern. The coating layer may be formed on at least a portion of the surface of the plurality of chips by spin coating, spray coating, or printing. In addition, the coating layer may be formed on at least a portion of the surface of the plurality of chips by physical vapor deposition, chemical vapor deposition, or electroplating.

The reinforcing material functions to withstand heat, pressure, and the like during the process of using the microfluidic paper chip of the present invention, and various materials known in the art may be used. Preferably polytetrafluoroethylene.

The method of the present invention described above is expressed by performing (a) printing of the electrode pattern, (b) cutting the electrode pattern, and (c) assembling the electrode pattern as each step, but the micro In order to fabricate the fluid paper chip, it may be printed as a form in which assembly or patterning is completed at the time of drawing a drawing of the electrode pattern in step (a). In the following examples, a method for manufacturing a modular microfluidic paper chip is described in detail, and a schematic method is illustrated in FIG. 3.

According to another aspect of the present invention, the present invention provides a modular microfluidic paper chip produced by the method of the present invention.

The modular microfluidic paper chip of the present invention uses the above-described method for manufacturing the modular microfluidic paper chip of the present invention, and the common contents between the two are omitted in order to avoid excessive complexity of the present specification.

The modular microfluidic paper chip includes an electrode pattern and an electrode pattern accommodating a fluid capable of accommodating the fluid and in which a fluid flows. Dropping the fluid and applying a voltage to the electrode pattern of the modular microfluidic paper chip of the present invention, it can be seen that the movement of the water droplets on the chip surface as shown in FIG. Therefore, it can be utilized for chemical synthesis of various stages by using various electrode patterns uniformed. According to a specific embodiment of the present invention, the modular microfluidic paper chip of the present invention can be used for nanoparticle synthesis.

The features and advantages of the present invention are summarized as follows:

(a) The present invention relates to a prefabricated paper chip capable of printing electrode patterns of various shapes on a sheet of paper at once and cutting and pasting necessary patterns.

(b) Unlike the conventional method of manufacturing a printed circuit board using a patterning agent or a patterning device, the method of the present invention only undergoes a simple printing process using an inkjet printer, thereby simplifying the patterning method and various types according to the assembly form of the electrode pattern. Chips can be produced.

(c) Thus, by using the method of the present invention, it is possible to provide a low-cost, economical and versatile microfluidic chip.

1 is a schematic diagram showing the principle of the electrowetting method. θ (V) means the contact angle in the case of the voltage V.
Figure 2 shows the results of measuring the contact angle in the paper chip using carbon nanotube (CNT) ink.
FIG. 3 schematically illustrates a manufacturing process of a modular microfluidic paper chip using inkjet printing.
4 schematically illustrates the movement of water droplets on the listed electrodes.
5 is a schematic view of five electrode patterns used in the production of paper chips of the present invention.
6 shows an example of assembling a CMT chip.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention in more detail and that the scope of the present invention is not limited by these embodiments in accordance with the gist of the present invention .

Example

1. Fabrication of carbon nanotube (CNT) ink

An ink was prepared using CNT to print the electrode pattern, and printed on paper and used as an electrode. In order to print the CNT electrode with an inkjet printer, a dispersant was first put into a multiwall CNT, and a ball milling operation was performed to uniformly disperse the CNT ink in water. In order to use it as an electrode, a certain amount of conductivity is required. In the present invention, the CNT electrode has sufficient conductivity to be used as an electrode by obtaining a resistance value of 1 kΩ / sq on ordinary A4 paper and a resistance of 200 kW / sq on photo paper. Showed.

2. DLTMC of digital microfluidic paper chip using carbon nanotube (CNT) ink Pattern making

In order to produce an electrode pattern for the production of a digital microfluidic paper chip, drawings are drawn using a program such as Photoshop or CAD, and an electrode of a desired shape is used on an ordinary A4 paper or photo paper using an inkjet printer and the CNT ink. Printed at tens of μm resolution.

Thereafter, as many electrode patterns as needed are cut out from the printed paper and patterned, and then parylene C is deposited to cover the insulating layer thereon, and spin coating of Teflon AF1600 is performed. I did it. When dropping water droplets on the electrode pattern of the paper chip on which parylene C and Teflon were deposited and applying a voltage (V), it was confirmed that the movement of the water droplets on the chip surface could be controlled as shown in FIG. 4.

On the other hand, in order to make a digital microfluidic chip, the dispensing point where water droplets are first made, the linear transport of the droplets on a straight line of electrodes, the merging of several droplets, and the merged droplets are mixed by movement. Since the movement of the mixing (mixing), etc. should be possible, in the present invention, a total of five kinds of electrode patterns were printed on one sheet of paper to produce DLTMC patterns as shown in Table 1.

DLTMC Pattern name pattern Usage
D

Dispensing: the starting point where the solution needed for the reaction is initially formed as a drop
L

Linear transport: The path by which water droplets (or solutions) move in a straight line along an electrode

T

Merging: T-shaped point where drops from both sides merge into one

M

Mixing: Droplets round a square electrode, mixing the solution inside


C

Cross: Multiple drops meet and merge or create different directions for the drops to move

3. CMT  Combining patterns Module chip  And synthesis of gold nanoparticles using the same

In Table 1, the module chips combining the CMT patterns were assembled using five patterns D and one each of patterns C, M, and T. Gold nanoparticles were synthesized using the pattern and three kinds of solutions (HAuCl ₄ , NaBH ₄ , and lysine). FIG. 5 shows an example of assembly of a module chip incorporating a CMT pattern. Table 2 shows operations at each point and formation of gold nanoparticles according to a moving path of a fluid on a module chip incorporating a CMT pattern.

Formation of Gold Nanoparticles step action Explanation


One

HAuCl ₄ from ① Solution and NaBH ₄ solution from ② meet and merge in + shape


2

The solution you meet mixes in a □ pattern (colloidal gold nanoparticles are formed).


3

At ④, lysine solution, a capping reagent, comes out and encounters the solution of step 2.


4

The drops made in step 3 are mixed in a round □ pattern.


5

The capped gold nanoparticle solution moves to ④ and is detected by interlocking with other devices. Unnecessary by-products go to ⑤

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the present invention. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (10)

Method of manufacturing a modular microfluidic chip comprising the following steps:
(a) printing an electrode pattern on a substrate using conductive ink and inkjet printing;
(b) cutting the printed electrode pattern;
(c) assembling the cut electrode patterns to manufacture a modular microfluidic chip; And
(d) coating a reinforcing material on the electrode pattern of the modular microfluidic chip.
The method of claim 1, wherein the conductive ink is a metal ink, a ceramic ink, or a molecular ink.
The method of claim 2, wherein the ceramic ink is a carbon nanotube (CNT) ink.
2. The method of claim 1, further comprising depositing an insulator to form an insulating layer on the electrode pattern after step (c).
5. The method of claim 4 wherein the insulator is glass, porcelain or polymer composition.
6. The method of claim 5 wherein the polymer composition is parylene.
delete The method of claim 1 wherein the reinforcing material is polytetrafluoroethylene.
The method of claim 1, wherein the substrate is paper or film.
10. A modular microfluidic paper chip produced by the method of any one of claims 1 to 6 and 8 to 9.

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